Solutions and Colligative Properties 2 Question 23
23. The freezing point of equimolal aqueous solutions will be highest for
$(1990,1 \mathrm{M})$
(a) $\mathrm{C}{6} \mathrm{H}{5} \mathrm{NH}_{3} \mathrm{Cl}$ (aniline hydrochloride)
(b) $\mathrm{Ca}\left(\mathrm{NO}{3}\right){2}$
(c) $\mathrm{La}\left(\mathrm{NO}{3}\right){3}$
(d) $\mathrm{C}{6} \mathrm{H}{12} \mathrm{O}_{6}$ (glucose)
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Solution:
- $\mathrm{C}{6} \mathrm{H}{5} \mathrm{NH}_{3} \mathrm{Cl}: i=2$;
$\mathrm{Ca}\left(\mathrm{NO}{3}\right){2}: \quad i=3$
$\mathrm{La}\left(\mathrm{NO}{3}\right){3}: \quad i=4 ;$
$\mathrm{C}{6} \mathrm{H}{12} \mathrm{O}_{6}: \quad i=1$
Lower the value of $i$, smaller will be the depression in freezing point, higher will be the freezing temperature, if molalities are equal. Hence, glucose solution will have highest freezing temperature.
